In IVF, One Embryo Is Better Than Two

Action Points

Explain to interested patients that in recent years, use of single embryo transfer has increased, but the live birth rate per woman has remained unchanged and the multiple birth rate has decreased substantially.

Explain that in this study, single embryo transfer appears to be less expensive than double embryo transfer, and is likely more cost-effective.

Note that the practice of implanting a single embryo has not been widely adopted because of doubts about its overall applicability, despite numerous reports about its efficacy.

OULO, Finland, March 25 -- For in vitro fertilization, single embryo transfer is more effective and less expensive than double embryo transfer, researchers here said.

Over the course of the study period, use of single embryo transfer increased while the live birth rate per woman remained unchanged and the multiple birth rate decreased substantially, Hannu Martikainen, M.D., and colleagues reported online in Human Reproduction.

"The present study provides evidence for the superiority of single embryo transfer over the traditional transfer of two embryos," the researchers said. "These data should encourage clinics to evaluate their embryo transfer policy and adopt single embryo transfer as their everyday practice."

The practice of implanting a single embryo has not been widely adopted because of fears that it will lower pregnancy rates per embryo transfer, increase the cost of treatments, and extend the time needed to achieve pregnancy.

However, there is "universal agreement" that multiple pregnancies, often a result of double embryo transfer, pose the biggest health risks from in vitro fertilization -- mainly from complications related to prematurity.

To compare the efficacy and cost-effectiveness of single versus double embryo transfer, the researchers looked at data on 1,510 women under age 40 treated in the Infertility Unit of the Oulu University Hospital between 1995 and 2004.

Treatment was split into two periods: 1995-2000, when single embryo treatment was rarely used (4.2% of women), and 2000-2004, when it was more routinely practiced (46.2% of women).

The researchers found that the pregnancy rate and live birth rate were higher in the single embryo transfer period, and multiple birth rate was significantly lower (P<0.0001).

And the incremental cost-effectiveness calculations, done in euros, showed that 19,889 were saved per live birth when single embryo transfers were more common than in the double embryo transfer period.

The higher pregnancy rate in the single embryo transfer period is likely attributable to more effective use of cryopreserved embryos, the researchers said. During the double embryo transfer period, embryos were frozen in groups of at least three. But during the latter period, embryos were typically frozen in individual vials.

Cost-efficacy is in line with other analyses that have found lower overall costs with single embryo transfer if expenses for pregnancy, neonatal, and pediatric care are taken into account.

However, the present study found that an increased use of frozen embryos, which is much cheaper than fresh cycles, occurred during the single embryo transfer period, adding to cost-effectiveness.

Another study in the same issue of Human Reproduction focused on cost-effectiveness of seven in vitro fertilization strategies, including single and double embryo transfer and combinations of the two.

They found that combinations of the treatments were not at all cost-effective.

"A choice has to be made between three cycles of single embryo transfer, double embryo transfer, or standard treatment," said Audrey Fiddelers, Ph.D., of the Academic Hospital Maastricht in the Netherlands, and lead author of the study. "It is not cost-effective to switch between these three treatment methods during the period of the three cycles of treatment."

Dr. Fiddlers said, however, that the choice of which procedure to create policy around depends on the society's willingness to pay.

At the lowest ceiling -- 7,350 -- three-cycle single embryo transfer has the highest probability of being most cost-effective. If a society is willing to pay 15,250, double embryo transfer would likely be most cost-effective, the researchers said

They noted that investigating the long-term costs and outcomes of in vitro fertilization singletons and twins will "give a clear answer to the question of which strategy is ultimately the most cost-effective."

Dr. Martikainen and colleagues concluded that with single embryo transfer, "outcome is improved, overall costs are decreased because of the incorporation of frozen embryo transfer cycles, and the incidence of multiple births is reduced more than twofold."

Dr. Martikainen's study was funded by Sigrij Juselius Foundation, the Academy of Finland, and Oulo University Hospital.

Dr. Fiddelers' study was supported by a grant from the Dutch Organization for Health Research and Development and the Dutch Health Insurance Board.

None of the researchers reported any conflicts of interest.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine

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